This invention relates to a silver halide film that, after imagewise exposure, is capable of being color developed either (1) in a wet-chemical multi-tank process at a temperature of 60xc2x0 C. or less by immersion in a phenylenediamine-containing developer solution or its equivalent, followed by desilvering in one or more subsequent solutions, or alternatively, (2) by thermal treatment of the film. This invention further relates to a silver halide film containing a blocked inhibitor which is an amido compound, said amido compound improving contrast when the film is thermally processed.
With the remarkable advances in the fields of solid-state imaging devices and various hard-copy printing technologies made in recent years, both electronic imaging systems and silver-halide photographic systems have become available to the consumer. At the present time, silver halide photographic systems tend to be superior with respect to high sensitivity and high image quality. One particular shortcoming of the silver-halide system, however, in comparison to electronic imaging systems is that the photographic element requires a so-called wet-development process that typically requires substantial volumes of processing solutions. Thus, the development of a xe2x80x9cdryxe2x80x9d process for a silver-halide color photographic system has been a goal of the photographic industry for many years.
A dry development process can be accomplished by the use of photothermographic elements such as described in Research Disclosure 17029 (Research Disclosure PT). Generally, in these kinds of systems, development occurs by reduction of silver ions in the photosensitive silver halide to metallic silver as in conventional non-thermal systems, but the developing agent is contained within the element, so that it is unnecessary to immerse the photographic element in an aqueous solution containing a developing agent. Research Disclosure PT discloses a type B photothermographic system, wherein the type B elements contain in reactive association a binder, a photosensitive silver halide (prepared in situ or ex situ) and an oxidation-reduction image forming combination comprising (1) a metallic salt or complex of an organic compound as an oxidizing agent, and (2) an organic reducing agent or developing agent. xe2x80x9cDry processingxe2x80x9d can also be accomplished by the use of diffusion transfer elements, see, for example EP 0762 201 (Matsumoto). One problem with such xe2x80x9cdryxe2x80x9d systems has been to achieve a commercially viable system that produces a quality of image comparable, in the eyes of the average film consumer, to traditional silver-halide film.
A practical color photothermographic system for general use with respect to consumer cameras would have significant advantages. Such film would be amenable to development at kiosks using dry equipment. A consumer could bring an imagewise exposed photothermographic film to a kiosk located at any one of a number of diverse locations, optionally independent from a wet-development lab, where the film could be developed and printed without any manipulation by third-party technicians. A consumer might also be more prone to owning and operating film development equipment at home if it was a dry system. Thus, the development of a successful photothermographic system could open up new opportunities for greater convenience and speed of film processing for a wider cross-section of consumers.
At this time thermal processors are not as available as are conventional aqueous processors, such as Kodak C-41 processors, which are widely available as a mature industry standard. The unavailability of thermal processors and associated equipment can hinder the adoption of dry photothermographic films by the consumer. Photothermographic films that could also be processed by Kodak C-41 chemistry or the like would overcome this disadvantage. Photothermographic films with such backwards compatibility would permit the consumer to enjoy the benefits unique to thermal processing (kiosk processing, low environmental impact, etc.) when thermal processing is accessible, and would also allow the consumer to take advantage of the current ubiquity of C-41 processing when thermal processing may not be accessible. However, differences in the requirements of films which are thermally processed vs. films which are wet processed make it difficult to provide one film which may be processed in two different ways.
In order to be acceptable for commercial application, it is necessary that a photothermographic system be stable before exposure, while avoiding desensitizing of the silver halide during storage. If these factors are not present the system may have increased fog and/or decreased Dmax after development. At the same time, the system must have sufficiently fast kinetics (including unblocking of the developing agent) when the exposed film is being developed by thermal activation. For a backwards compatible film, the requirement might be that the components in the photothermographic film, designed exclusively for the dry photothermographic development (for example the blocked developing agent and anti-fogging agents) do not adversely affect or interfere with the sensitometry of the film when it is developed by traditional wet-processing.
In photothermographic film systems used to capture full color images, once the film has been developed the scanning of the scene luminance content is only possible over a limited density range, determined by the scanner design. If the film densities are too high, scanning is either not possible or becomes subject to signal to noise problems and scene information is lost. It is essential to design color photothermographic films to have sufficient latitude; that is, to be capable of recording all required scene luminance information in a density range that can be scanned. Therefore, such film designs must have a lower gamma and so reach a lower maximum density in each color record than is normal for conventional films.
It is well known that certain heterocyclic molecules with relatively acidic hydrogen atoms bonded to a ring nitrogen or an adjacent sulfur atom act as development restrainers or inhibitors in photographic film and paper systems. Development inhibitors are utilized to either slow or stop development of silver halide grains. They can be used to correct unwanted dye absorption, improve sharpness and reduce granularity of films. Various methods have been described for chemically blocking these inhibitors so that they are stable to storage in the film but can be released in a timely fashion upon development. Release of inhibitor typically is achieved under aqueous alkaline conditions by reaction with base or other nucleophile in the processing solution. In particular, blocked inhibitors have found use in image transfer systems. Research Disclosure article 13118, March 1975 and U.S. Pat. Nos. 4,255,510 and 4,256,881 describe materials that use alkali-hydrolyzable groups to block the inhibitors, specifically N-mono substituted and N,N-disubstituted amido groups. Other methods of non-imagewise release involve reaction of a suitably blocked inhibitor with base or other nucleophile in the processing solution, such as described in U.S. Pat. No. 5,354,650, are known but have not been found useful in photothermography.
In conventional photographic systems, such as color negative films, the addition of free inhibitors, even in small quantities, leads to loss of sensitivity. It is therefore useful to release inhibitors imagewise by chromogenic development using, for example, Development Inhibitor Releasing (DIR) couplers. DIR couplers are used to control film response to light by reducing photographic gamma in an imagewise fashion. However, in many cases DIR couplers are not effective gamma reducers in photothermographic systems. Therefore it is necessary that the photothermograhic system include other types of inhibitors which are effective gamma reducers.
What is needed is a backwards compatible film which has a low enough gamma to satisfy the wide latitude needs of a photothermographic system without adversely affecting sensitivity when the same film is wet processed.
This invention provides a method of processing an imagewise exposed color photographic film, said film having at least three light-sensitive units which have their individual sensitivities in different wavelength regions, each of the units comprising at least one light sensitive silver halide emulsion and an image dye coupler, which method comprises contacting the imagewise exposed color photographic film with an aqueous solution containing a non-blocked developing agent at a temperature of between 30 to 60xc2x0 C.; and
wherein said film further comprises an incorporated reducing agent, at least one organic silver salt and an amido compound of Formula I: 
wherein INH is a development inhibitor;
LINK is a linking or timing group and m is 0, 1, or 2; and
R1 and R2 independently are a hydrogen atom or an aliphatic, aromatic or heterocyclic group, or R1 and R2 together with the nitrogen to which they are attached represent the atoms necessary to form a 5- or 6-membered ring or multiple ring system, or R1 and R2 are independently a xe2x80x94C(xe2x95x90O)(LINK)mxe2x80x94INH group, or are substituted with a xe2x80x94NR3C(xe2x95x90O)xe2x80x94(LINK)mxe2x80x94INH, with R3 being defined the same as R1 or R2, with the proviso that only one of R1 and R2 can be a hydrogen atom;
wherein the reducing agent is substantially unreactive in the aqueous color development step described above, but wherein color development of the same imagewise exposed film is capable of being alternatively and comparatively obtained, without any externally applied developing agent, by heating said film to a temperature above about 80xc2x0 C. essentially in the absence of aqueous solutions, such that the incorporated reducing agent reacts to form dye by reacting with the image dye couplers; with the proviso that the amido compound effectively reduces contrast when the film is heated above 80xc2x0 C. but does not substantially reduce contrast when the film is processed by contacting the imagewise exposed color photographic film with a non-blocked developing agent under aqueous conditions, at a temperature of between 30 to 60xc2x0 C.
This invention further provides a method of processing a commercial quantity of color photographic film sold to camera users over a given period of time, which film has been imagewise exposed in a camera, said film having at least three light-sensitive units which have their individual sensitivities in different wavelength regions, each of the units comprising at least one light sensitive silver halide emulsion, an image dye coupler and a blocked developing agent, wherein the method comprises:
(a) processing a first substantial portion of said quantity of film by a method comprising contacting the imagewise exposed color photographic film with an aqueous solution containing a non-blocked p-phenylenediamine developing agent, at a temperature of 30 to 60xc2x0 C., in order to form image dye in the film by reaction of the non-blocked p-phenylenediamine developing agent with the image dye couplers contained in the light sensitive units, followed by desilvering said film in one or more desilvering solutions to remove unwanted silver and silver halide, thereby forming a color negative image; and
(b) processing second substantial portion of said quantity of film by a method comprising heating said film to a temperature above about 80xc2x0 C., without any externally applied developing agent, such that the blocked developing agent becomes unblocked to form a phenylenediamine developing agent, whereby the unblocked developing agent forms image dyes by reacting with the image dye couplers to form a color negative image; wherein the color photographic film further comprises at least one organic silver salt and an amido compound of Formula I: 
wherein INH is a development inhibitor;
LINK is a linking or timing group and m is 0, 1 or 2; and
R1 and R2 independently are a hydrogen atom or an aliphatic, aromatic or heterocyclic group, or R1 and R2 together with the nitrogen to which they are attached represent the atoms necessary to form a 5- or 6-membered ring or multiple ring system, or R1 and R2 are independently a xe2x80x94C(xe2x95x90O)(LINK)mxe2x80x94INH group, or are substituted with a xe2x80x94NR3C(xe2x95x90O)xe2x80x94(LINK)mxe2x80x94INH, with R3 being defined the same as R1 or R2, with the proviso that only one of R1 and R2 can be a hydrogen atom;.
This invention also provides an article of manufacture comprising a packaged color photographic film which photographic film has at least three light-sensitive units which have their individual sensitivities in different wavelength regions, each of the units comprising at least one light-sensitive silver halide emulsion layer, an image dye-coupler, and a blocked phenylenediamine developing agent, wherein the film is enclosed by a package on which indicia indicates that the film may be processed by either a wet-chemical process or a thermal processing method; and wherein the film further comprises, at least one organic silver salt and an amido compound of Formula I: 
wherein INH is a development inhibitor;
LINK is a linking or timing group and m is 0, 1 or 2; and
R1 and R2 independently are a hydrogen atom or an aliphatic, aromatic or heterocyclic group, or R1 and R2 together with the nitrogen to which they are attached represent the atoms necessary to form a 5- or 6-membered ring or multiple ring system, or R1 and R2 are independently a xe2x80x94C(xe2x95x90O)(LINK)mxe2x80x94INH group, or are substituted with a xe2x80x94NR3C(xe2x95x90O)xe2x80x94(LINK)mxe2x80x94INH, with R3 being defined the same as R1 or R2, with the proviso that only one of R1 and R2 can be a hydrogen atom;.
This invention provides a film with enhanced backwards compatibility. The amido compound contained in the film enables the necessary contrast control during photothermographic processing, but has no effect during aqueous alkaline processing where a large release of inhibitor would result in sensitivity losses.